Diamond impregnated wire has been previously used for certain cutting operations in which the wire was run in a straight line and the work being cut was pressed against the wire in one direction only. Such prior diamond impregnated wire cutting machines were used to cut slices from various types of materials such as carbon and graphite compounds, tungsten and boron, fibers, paper and titanium honeycomb, gem stones, "moon rocks," and various materials having a hardness up to ten on the mohs scale for use in industrical research and development laboratories, production departments, semi-conductor factories, tube mills and tool plants. Such prior diamond impregnated wire included a wire core of high tensile strength, a matrix or coating of electrolytic copper on the wire core, and impregnation of the copper matrix with a diamond powder having a particle size in the range of from 6 to 100 microns depending upon the diameter of the wire. Diamond impregnated wire is available with diameters of 0.003 inches, 0.008 inches, and 0.0155 inches. The diamond particles may be made of synthetic or natural diamond material.
In prior proposed diamond wire cutting machines the diamond wire was guided through the cutting zone by a pair of pulleys disposed on opposite sides of the cutting zone. The wire was of fixed length, such as 100 feet, and was fastened to a single rotatable drum about which the wire was wound. The drum was provided axial movement so that the wire was fed from the drum and also fed onto the drum in virtually the same plane as the guide pulleys so that the wire would not be disposed at an angle to the guide pulleys and thereby cause rapid wear thereof. The rotatable wire carrying drum was driven by a reversable motor so that when the end of the wire was approached the motor would reverse the direction of rotation of the drum and the wire passing through the cutting zone would be reversed in direction but maintained under the same tension and the same cutting speed.
While diamond impregnated cutting wire has been used in such machines for making straight, smooth cuts with minimum loss of material and has been used in manually operated hack saw frames, use has not been made of diamond impregnated wire for cutting shapes having X, Y dimensions because change in laterally directed forces on the wire passing through the cutting zone caused the imposition of similarly directed forces on the guide pulleys which were fixed in position. Since the diamond impregnated wire was required to be at a selected tension and although the force of the work against the wire was sometimes very minimal, abnormal wear on the pulleys occured and in addition precise cutting of the work within acceptable tolerances was not practical. However, it is recognized that diamond impregnated cutting wire is capable of cutting work at any place along the circumference of the wire. The use of diamond impegnated cutting wire is therefore advantageous over cutting machines utilizing band saws or scroll-type saws.